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Dirty underpants, a mannequin wearing socks, an air conditioner and a still-working iPhone were among some of the stranger items of trash picked up from New Jersey's beaches last year.

Clean Ocean Action is marking its 25th year of beach sweeps in the Garden State. Thursday afternoon, the coastal environmental group will release its full report on all the disgusting, dangerous and just flat-out weird trash that made its way onto the state's beaches over the last quarter-century.

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The group says plastics have always accounted for the largest percentage of cleaned-up garbage — about 77 percent. Many plastic items can kill marine life by choking them or tangling their intestines.

"People think these single-use plastic items are disposable, but they're really not," said Tavia Danch, the group's pollution prevention coordinator. "That's one of the main points we hope to get across."

Cigarette filters account for 13 percent of the trash.

Since the group's first beach sweep in 1985, nearly 4 million pieces of trash have been picked up and disposed of or recycled.

When they first started, plastic six-pack beverage can rings were a major problem up and down the coast. They were particularly lethal to sea turtles and young seals, who would become entangled in them and choke.

In recent years, however, volunteers have found much fewer six-pack rings, mainly because more beverages are sold in cardboard containers.

But balloons, particularly Mylar-coated ones, are on the rise. People either let them go on purpose or they slip out accidentally, fly for miles and end up in rivers or the ocean, endangering marine life.

Clear plastics in general are dangerous for turtles, which mistake them for jellyfish and eat them, often with fatal results.

Other items picked up in recent years include toilet seats, a pregnancy test (result unclear), bags of pet waste, an 8-track tape, half a Barbie doll, a tube of denture cement, a jockstrap and fake breasts.